whenever

Shorthand for watching a signal to be true.

Usage

use leptos::*;
use leptos::logging::log;
use leptos_use::whenever;

pub fn Demo() -> impl IntoView {
let (is_ready, set_ready) = create_signal(false);

whenever(move || is_ready.get(), |v, _, _| log!("{}", v));

    view! { }
}

Callback Function

Same as watch, the callback will be called with callback(input, prev_input, prev_return).

use leptos::*;
use leptos::logging::log;
use leptos_use::whenever;

pub fn Demo() -> impl IntoView {
let (is_ready, set_ready) = create_signal(false);
whenever(move || is_ready.get(), |value, prev_value, _| {
    log!("before: {prev_value:?}; now: {value}");
});

    view! { }
}

Computed

Same as watch, you can pass a getter function to calculate on each change.

use leptos::*;
use leptos::logging::log;
use leptos_use::whenever;

pub fn Demo() -> impl IntoView {
let (counter, set_counter) = create_signal(0);
whenever(
    move || counter.get() == 7,
    |_, _, _| log!("counter is 7 now!"),
);

    view! { }
}

Options

Options and defaults are same as watch_with_options.

use leptos::*;
use leptos::logging::log;
use leptos_use::{WatchOptions, whenever_with_options};

pub fn Demo() -> impl IntoView {
let (counter, set_counter) = create_signal(0);
whenever_with_options(
    move || counter.get() == 7,
    |_, _, _| log!("counter is 7 now!"),
    WatchOptions::default().immediate(true),
);

    view! { }
}

Server-Side Rendering

On the server this works just fine except if you throttle or debounce in which case the callback will never be called except if you set immediate to true in which case the callback will be called exactly once.

Source

Source • Docs